Modern vehicles utilize smaller and/or turbocharged engines in order to enhance fuel economy and fuel emissions. However, these engines produce less thermal waste heat and therefore suffer from a decreased thermal capacitance and longer engine warm-up times. The decreased production of heat within the engine system further propagates into a slow increase of the coolant and engine oil temperatures, particularly in cold ambient temperatures (e.g., less than 15 degrees Centigrade) and in sub-zero conditions where cabin comfort becomes a primary concern.
In order to mitigate this problem, previous solutions have used additional devices such as: glow plug heaters, electric air heaters, fuel fired heaters, coolant control valves and enhanced engine management software (e.g., using spark retard). However, additional devices can be costly and typically operate at the expense of fuel economy. A charge air cooler (CAC) is also often used to cool air after it has passed through a turbocharger, but before it enters the engine. The lower temperature air generates more optimal power during the combustion process within the engine. However, the CACs are frequently water cooled by a dedicated and separate coolant circuit which incorporates an air/coolant heat exchanger, radiator and electric water pump.
The inventors have recognized disadvantages with the above approaches and herein disclose a system and method for managing thermal flow particularly in relation to the heating of an engine of a vehicle. In one particular example, the engine system comprises a turbocharger adapted to compress intake air prior to the intake air being received at the engine, a charge air cooler device operatively interposing the turbocharger and the engine, wherein a coolant system is operable in three different modes to control the flow of heat in the engine system. For example, the coolant system may operate in a first mode to provide a first coolant circuit for cooling the engine and a second separate coolant circuit for cooling air passing through the charge air cooler device, whereas the coolant system may operate in a second mode to provide a third coolant circuit in which coolant from the engine is transmitted to the charge air cooler device for heating before being recirculated back to the engine to heat the engine.
The present description may provide several advantages. In particular, the approach may enhance engine warm-up without costly additional devices. Furthermore, advantages are offered in that engine warm-up is achieved without adversely affecting vehicle fuel economy, especially in cold ambient temperatures. Therefore, enhanced fuel economy may be obtained through enhanced combustion stability in severely cold ambient temperatures. In addition, the engine system described is straightforward to implement.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings. It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.